I am creating an image upload script, and i want the files to be renamed into random letters and numbers. For example if I uploaded 123.jpg, I would want it to turn out like ab6482cd.jpg.

Can anybody help me and tell me how to do it?

Here is a script renaming files based on the size, date and time of upload:
http://www.acecoolco.com/media_tutorialshow.php?id=55

and there is a random name script on http://www.bloodys.com/phpscripts.php

Thanks very much mate.